[Image above] Credit: NIST
An important step towards next-generation ultra-compact photonic and optoelectronic devices has been taken with the realization of a 2-D excitonic laser. Scientists with the U.S. DOE’s Lawrence Berkeley National Lab embedded a monolayer of tungsten disulfide into a special microdisk resonator to achieve bright excitonic lasing at visible light wavelengths.
A group of researchers at the Institute of Laser Engineering at Osaka University, in cooperation with Screen Holdings Co. Ltd., succeeded in visualizing changes in defect density on the surface of GaN through the laser terahertz emission microscope (LTEM), which measures THz waves generated by laser emission. This group’s discovery shows that LTEM is useful as a new method for evaluating the quality of wide-gap semiconductors.
A team led by University of Wisconsin-Madison researchers recently described the precursor phases of nacre formation at both the atomic and nanometer scale in red abalone marine mollusks. Using synchrotron radiation, researchers directly observed the chemical transformation of amorphous calcium carbonate to the mineral aragonite, which manifests itself as nacre by layering microscopic polygonal aragonite tablets like brickwork to underpin the lustrous and durable biomaterial.
Phosphors are efficient light emitters but they’re not optimal for high-speed communications because they turn on and off slowly. Researchers from Brown and Harvard have now found a way to modulate light from phosphor emitters orders of magnitude faster using phase-change materials, which could make phosphors useful in a range of new optoelectronic applications.
In 2010, Michael Escuti received NSF funding to study and make novel hologram technologies. He created a tool that did much more. The technology is a new way to manipulate light, with applications from studying alien worlds to making cellphones more energy efficient. Escuti and his team developed a direct-write laser scanner (DWLS), “which allows us to create nearly perfect geometric phase holograms.”
In the 21st century, photonic devices will enhance or even replace the electronic devices that are ubiquitous in our lives today. But there’s a step needed before optical connections can be integrated into telecommunications systems and computers: researchers need to make it easier to manipulate light at the nanoscale. Researchers at Harvard have done just that, designing the first on-chip metamaterial with a refractive index of zero, meaning that the phase of light can travel infinitely fast.